[3−4−69]\left[\begin{array}{cc}3 & -4 \\-6 & 9\end{array}\right][3−6−49]
[3003∣\left[\begin{array}{ll}3 & 0 \\0 & 3\end{array} \mid\right.[3003∣
13[3−4−69]\frac{1}{3}\left[\begin{array}{cc}3 & -4 \\-6 & 9\end{array}\right]31[3−6−49]
[1001]\left[\begin{array}{ll}1 & 0 \\0 & 1\end{array}\right][1001]